netdev - Re: [PATCH net-next v2] enic: use atomic_t instead of spin

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Message-Id: <20150625.052327.1461706804571236235.davem@davemloft.net>
Date:	Thu, 25 Jun 2015 05:23:27 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	_govind@....com
Cc:	netdev@...r.kernel.org, ssujith@...co.com, benve@...co.com
Subject: Re: [PATCH net-next v2] enic: use atomic_t instead of spin_lock in
 busy poll

From: Govindarajulu Varadarajan <_govind@....com>
Date: Thu, 25 Jun 2015 16:02:04 +0530

> We use spinlock to access a single flag. We can avoid spin_locks by using
> atomic variable and atomic_cmpxchg(). Use atomic_cmpxchg to set the flag
> for idle to poll. And a simple atomic_set to unlock (set idle from poll).
> 
> In napi poll, if gro is enabled, we call napi_gro_receive() to deliver the
> packets. Before we call napi_complete(), i.e while re-polling, if low
> latency busy poll is called, we use netif_receive_skb() to deliver the packets.
> At this point if there are some skb's held in GRO, busy poll could deliver the
> packets out of order. So we call napi_gro_flush() to flush skbs before we
> move the napi poll to idle.
> 
> Signed-off-by: Govindarajulu Varadarajan <_govind@....com>

Applied, thanks.
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